The blasts, one in a heavily guarded area close to a revered shrine, raised the week's death toll to more than 100 and cast further doubt on the divided government's ability to secure the country after the American withdrawal.

Black plumes of smoke filled the sky over Baghdad's northern Kadimiyah neighborhood, where the shrine to eighth-century saint Imam Moussa al-Kadhim draws hundreds of thousands of pilgrims each year. One of the bombs tore into throngs of people who packed the streets nearby, carrying aloft symbolic coffins and beating their chests in mourning to mark his martyrdom.

Three days before, nearly two dozen coordinated bombs around the country killed 72 people. Al-Qaida's Iraqi affiliate on Saturday claimed responsibility for that attack, which marked one of the deadliest days in Iraq since the last U.S. troops left in December.

The fierce wave of bombings targeting Shiites suggest that the al-Qaida-allied Sunni militants are stepping up their periodic attacks — which recently have come every few weeks — to try to exploit sectarian cracks in the elected government of Prime Minister Nouri al-Maliki and possibly spark another round of the violence between Sunni and Shiite Muslims that brought Iraq to the brink of civil war only a few years ago.